An important feature of golf cart batteries is the number of minutes they will perform before needing to be recharged. A certain manufacturer advertises batteries that will run, under a 75 amp discharge test, for an average of 125 minutes with a standard deviation of 5 minutes.
a. Find an interval that contains at least 90% of the performance periods for batteries of this type.
b. Would you expect many batteries to die out in less than 100 minutes? Why?
2) From a box containing five white and four red balls, two balls are selected at random without replacement. Find the probabilities of the following events.
a. Exactly one white ball is selected.
b. At least one white ball is selected.
c. Two white balls are selected, given that at least one white ball is selected.